Fuel Cell Arrangement for an H2/O2 Fuel Cell

Abstract

The invention relates to a fuel cell arrangement (10) having an anode (26) connected to an H2 inflow (48) and a cathode (30) connected to an O2 inflow (50), wherein a differential pressure control device (52) is arranged between the H2 inflow (48) and the O2 inflow (50) for controlling a differential pressure between the H2 inflow (48) and the O2 inflow (50), the differential pressure control device (52) having a fluid connection (54) between the H2 inflow (48) and the O2 inflow (50) in which a deflectable diaphragm (56) is arranged, to which a pin (64) is coupled which, when the diaphragm (56) is deflected, opens a valve (58) arranged in the H2 inflow (48).

Claims

1. A fuel cell arrangement (10) for an H2/O2 fuel cell (16), having: an anode (26), at which H2 (14) is oxidized during operation, and which is connected to an H2 inflow (48) for supplying H2 (14) to the anode (26), wherein a valve (58) having a valve seat (62) and a valve element (60) is arranged in the H2 inflow (48), which interact in a closing position in order to interrupt an inflow of H2 (14) from the H2 inflow (48) to the anode (26), a cathode (30), at which O2 (28) is reduced during operation, and which is connected to an O2 inflow (50) for supplying O2 (28) to the cathode (30), wherein a differential pressure control device (52) is arranged between the H2 inflow (48) and the O2 inflow (50) for controlling a differential pressure between the H2 inflow (48) and the O2 inflow (50), the differential pressure control device (52) having a fluid connection (52) between the H2 inflow (48) and the O2 inflow (50) in which there is arranged a diaphragm (56) for sealing the fluid connection (54) which can be deflected by a deflection force (F.sub.A) acting due to a pressure difference (p) between the H2 inflow (48) and the inflow (50), wherein a pin (64) is coupled to the deflectable diaphragm (56) and the valve element (60) in such a manner that the pin (64), when the diaphragm (56) is deflected in the direction of the H2 inflow (48), presses the valve element (60) away from the valve seat (62) in the opening direction.

2. The fuel cell arrangement (10) according to claim 1, characterized in that a second deflectable diaphragm (66) for sealing the fluid connection (54) is arranged in the fluid connection (54) at a distance from the diaphragm (56) which can be deflected by the deflection force (F.sub.A) acting due to the pressure difference (41) between the H2 inflow (48) and the O2 inflow (50), which deflectable diaphragm forms a first diaphragm (56).

3. The fuel cell arrangement (10) according to claim 2, characterized in that the first diaphragm (56) seals the fluid connection (54) toward the H2 inflow (48), wherein the second diaphragm (66) seals the fluid connection (54) toward the O2 inflow (50).

4. The fuel cell arrangement (10) according to claim 2, characterized in that due to the arrangement of the first and second diaphragm (56, 66) at a distance from one another in the fluid connection (54) a pressure transmission volume (68) is formed, which is filled with a pressure transmission fluid (70) which transmits the deflection force (F.sub.A) exerted by the pressure difference (p) between the H2 inflow (48) and the O2 inflow (50) from the second diaphragm (66) to the first diaphragm (56).

5. The fuel cell arrangement (10) according to claim 4, characterized in that the first diaphragm (56) and the second diaphragm (66) have different active surfaces (A.sub.w) for accepting the deflection force (F.sub.A).

6. The fuel cell arrangement (10) according to claim 5, characterized in that a first active surface (A.sub.w) of the first diaphragm (56) is smaller than a second active surface (A.sub.w) of the second diaphragm (66).

7. The fuel cell arrangement (10) according to claim 1, characterized in that the valve (58) has a compression spring (72) which is arranged in the H2 inflow (48) and exerts a spring force (F.sub.F) on the valve element (60), which biases the valve element (60) in a closing direction onto the valve seat (62).

8. The fuel cell arrangement (10) according to claim 6, characterized in that an actuator (74) for controlling the spring force (F.sub.F) of the compression spring (72) is provided.

9. The fuel cell arrangement (10) according to claim 8, characterized in that the actuator (74) is configured by an actuatable piezo actuator, an actuatable electromagnetic actuator or by a controllable electromotor having a spindle.

Description

[0030] Advantageous configurations of the invention are explained in greater detail below, with reference to the appended drawings, wherein:

[0031] FIG. 1 shows a schematic overview of a fuel cell arrangement having a fuel cell and a hydrogen metering valve;

[0032] FIG. 2 shows a schematic detailed representation of a partial region of the fuel cell arrangement from FIG. 1 in a first embodiment;

[0033] FIG. 3 shows a schematic detailed representation of a partial region of the fuel cell arrangement from FIG. 1 in a second embodiment; and

[0034] FIG. 4 shows a schematic overview of a fuel cell arrangement having a hydrogen metering valve from the prior art.

[0035] FIG. 1 shows an overview of a fuel cell arrangement 10 which has an H2/O2 fuel cell 16 which comprises an anode 26 and a cathode 30. Hydrogen 14 is oxidized in the anode 26, while oxygen 28 is reduced in the cathode 30. In order to feed the anode 26, a hydrogen tank 12 is provided, which stores the hydrogen 14 at high pressure. The hydrogen 14 is supplied by means of lines 22, in which a shutoff valve 18 and a pressure reducer 20 are arranged, to a hydrogen metering valve 24 which itself adjusts a pressure of the hydrogen 14 in an H2 inflow 48 to the anode 26 and, therefore, in the anode 26. Oxygen 28 is supplied by means of an O2 inflow 50 to the cathode 30.

[0036] An inlet 38 of the anode 26 is connected to an outlet 36 of the anode 26 by means of a gas blower 34, in order to make possible a recirculation of the hydrogen 14. If, due to the reaction between the hydrogen 14 and oxygen 28, a large part of the hydrogen 14 is consumed, the consumed gas from the anode 26 can be let out of the anode 26 by means of a release valve 40. The hydrogen metering valve 24 then meters fresh hydrogen 14 to the anode 26 by means of the H2 inflow 48.

[0037] The hydrogen metering valve 24 is configured as a differential pressure control device 52 which controls a pressure difference p between the H2 inflow 48 and the O2 inflow 50.

[0038] The construction of a first embodiment of the differential pressure control device 52 is shown in greater detail in a representation of the fuel cell arrangement 10 in FIG. 2.

[0039] The differential pressure control device 52 has a fluid connection 54 between the H2 inflow 48 and the O2 inflow 50. A first diaphragm 56, which can be deflected from its position by a pressure difference p between the H2 inflow 48 and the O2 inflow 50 and a deflection force F.sub.A acting as a result, is arranged in the fluid connection 54.

[0040] A passive valve 58 is arranged in the H2 inflow 48, which has a valve element 60 and a valve seat 62. In a closing position, the valve seat 62 and the valve element 60 interact such that the valve 58 is closed.

[0041] A pin 64 is coupled to the first diaphragm 56 and the valve element 60. As soon as the first diaphragm 56 is deflected in the direction of the H2 inflow 48, the first diaphragm 56 presses the pin 64 onto the valve element 60 such that the latter raises from the valve seat 62 and the valve 58 opens.

[0042] As a result, the H2 inflow 48 to the anode 26 is released and hydrogen 14 can flow to the anode 26.

[0043] A second diaphragm 66 is arranged at a distance from the first diaphragm 56 in the fluid connection 54, which can likewise have its position changed due to the pressure difference p.

[0044] The first diaphragm 56 seals the fluid connection 54 toward the H2 inflow 48, while the second diaphragm 66 seals the fluid connection 54 toward the O2 inflow 50. Due to the arrangement at a distance of the two diaphragms 56, 66 in the fluid connection 54, a pressure transmission volume 68 is formed in the fluid connection 54, wherein said pressure transmission volume 68 is filled with a pressure transmission fluid 70. If the second diaphragm 66 is then deflected in the direction of the H2 inflow 48 due to the pressure difference Op between the H2 inflow 48 and the O2 inflow 50, the pressure transmission fluid 70 transmits the deflection force F.sub.A acting as a result from the second diaphragm 66 to the first diaphragm 56, which consequently opens the valve 58.

[0045] The greater the pressure in the O2 inflow 50 is, the more the second diaphragm 66 is deformed and the more said deformation acts on the pressure transmission fluid 70 in the pressure transmission volume 68. The pressure transmission fluid 70 continues to act on the first diaphragm 56 in the region of the H2 inflow 48. From the side of the H2 inflow 48, the pressure in the region of the anode 26 acts on the first diaphragm 56 such that the position of the first diaphragm 56 depends on the pressure difference p between the O2 inflow 50 and the H2 inflow 48. The dependence of the position of said first diaphragm 56 on the pressure difference p can be constructively adjusted by means of the ratios of the active surfaces A.sub.w of the diaphragms 56, 66. If, for example, the first diaphragm 56 has a smaller active surface A.sub.w than the second diaphragm 66, a small pressure difference p also produces a relatively large deflection of the first diaphragm 56 and, consequently, a rapid opening of the valve 58.

[0046] Due to the change in position of the first diaphragm 56, the pin 64 presses the valve element 60, as a result of which the position of the valve element 60 is changed relative to the valve seat 62 and, consequently, a cross-section is released. As a function of the resulting cross-section, the supply of the hydrogen 14 into the anode 26 is regulated.

[0047] The valve 58 additionally has a compression spring 72 which is arranged in the H2 inflow and exerts a spring force F.sub.F on the valve element 60, as a result of which the valve element 60 is biased in a closing direction onto the valve seat 62. Thanks to the spring force F.sub.F, the bias of the valve element 60 can be adjusted, such that the deflection force F.sub.A which is needed to raise the valve element 60 from the valve seat 62 can be influenced by means thereof.

[0048] The quantity of hydrogen which is supplied to the anode 26 therefore results from the force equilibrium between the prevailing pressure in the O2 inflow 50, the prevailing pressure in the H2 inflow 48, the active surfaces A.sub.w on the valve element 60 and the valve seat 62 as well as the spring force F.sub.F of the compression spring 72, which holds the valve element 60 in its position, and which acts, from the side opposite the pin 64, on the valve element 60.

[0049] By means of said force equilibrium, a constant pressure difference p between the anode 26 and the cathode 30 can be adjusted during the operation of the fuel cell 16.

[0050] FIG. 3 shows a schematic representation of a second embodiment of the fuel cell arrangement 10, which has substantially the same construction as the first embodiment which is shown in FIG. 2. In the case of the second embodiment, an actuator 74 is merely additionally provided, which can control the spring force F.sub.F of the compression spring 72. The force equilibrium can therefore be influenced by the additional actuator 74, which can be configured, for example, by a piezo actuator, an electromotor having a spindle or an electromagnet. As a result, the pressure difference p to be controlled between the cathode 30 and the anode 26 can additionally be tweaked.